The use of gases in medical applications is widespread. One of the gases often administered to patients for medical reasons is oxygen. In view of the fact that administering oxygen is often essential for preventing damage to tissue, avoiding life-threatening situations or saving a patient from a life-threatening situation, hospitals distribute oxygen using a pipeline network up to the bed of nearly each patient. The conventional form of administering oxygen through a pipeline network is in a continuous manner. A flow meter can be set to the flow rate that the patient needs (1 l/min up to 15 l/min continuously or higher). This way the oxygen flows continuously from the source to the patient via a nasal cannula during inhaling and exhaling. The flow meter is plugged into the low-pressure oxygen socket (usually between 3.6 and 5.5 bars) on the wall behind the patient's bed. A moisturizer can be attached to the bottom side to prevent drying up of the nasal mucous membrane.
The lungs can only utilise the first phase of inhalation to exchange oxygen with the blood circulation. It is clear that oxygen can no longer be ‘consumed’ during the expiration phase (exhalation). However, during the last phase of inhalation too, only the large bronchial tube that does not participate in the diffusion process of oxygen is filled. Gas valves for the pulsating supply of medical gases are based on this principle: oxygen is purposefully administered during the first phase of inhalation by the patient. This way a maximum oxygen intake is achieved and the oxygen that is not used is minimised. This results in savings without impacting the oxygen therapy.
Various gas valves have been developed during the past 20 years which are based on the principle of discontinuous oxygen administration in order to increase the mobility of patients that use oxygen cylinders at home and/or to increase the autonomy of recipients. After all, the use of gas valves for mobile patients saves oxygen, which results in a lower consumption and consequently creating longer autonomy, i.e. 3 to 5 times longer than the autonomy achieved with continuous administration.
Most gas valves are based on a regulating system in which nasal inhalation activates the gas valve. The underpressure activates and opens an oxygen valve through which an oxygen pulse (aka bolus) is generated. Detecting the inhalation and supplying the oxygen occurs by means of a nasal cannula. A nasal cannula can be a one-channel system (detection and supply occur through the same channel) or a two-channel system in which one channel is used for detecting the inhalation and the other channel is used for supplying the oxygen.
EP1325762 describes a one-channel system for the supply of medical gases. The system provides an oxygen bolus in case of detecting inhalation and provides a period of delay following the oxygen bolus in order to avoid a redundant double oxygen pulse.
U.S. 2008/0173304 A1 describes a pneumatic valve for medical gases that combines the typical advantages of operating a one-channel nasal cannula and a two-channel nasal cannula. The pneumatic medical gas valve generates a gas pulse based on the detection of nasal inhalation and prevents generating a double pulse by applying a pneumatically induced delay.
U.S. 2007/0017520 A1 describes a device for administering oxygen in which gas is released in case of inhalation and in which the gas flow is interrupted by a dedicated pneumatic system.
FR2813799 A1 describes a gas valve for oxygen in which a continuous flow and a pulsating administration are possible. The gas valve consists of two channels to the patient: one channel takes care of supplying the oxygen and the other channel ensures the detection of inhalation. Furthermore, the gas valve has a pressure regulator so that the gas valve can be connected to a gas cylinder under high pressure.
U.S. Pat. No. 4,932,402 describes a gas valve that provides a user-specific oxygen supply based on the measured breathing of the patient using an electronic control. Moreover, the system is customised to switch to a continuous oxygen flow in case of power failure or poor operation.
U.S. Pat. No. 5,038,770 describes another valve that has a safeguard in case the control system for pulsating supply fails or if there is a power failure.
Most of the aforementioned systems are suitable for home use in which a gas cylinder is used.
Hospitals have to cope with a large circulation of patients. That means that systems with a complex adjustment to the patient's individual needs are time-consuming for the patient and for the medical staff. In addition, hospitals have a large variety of medical gas therapies that are used even during the treatment of one and the same patient. This differs significantly from home devices used by an individual patient in which the patient usually sets the correct adjustment only once (or a limited number of times) and after that, he/she can usually use the same adjustment. In addition, the current technology does not enable generating a pulse dosage of more than 6 l/min. The result is that the available economizer valves are not suitable for all patients and consequently, cannot be used efficiently in hospitals.
Therefore, a valve for checking the flow of medical gas that can be used effectively in specific institutional environments such as hospitals is required. In addition, there is a need for a medical gas flow controlling valve that enables a larger flow of medical gas (e.g., more than 6 l/min).